While organ transplantation even after a cerebral death has not readily been put into action in Japan, a 3-dimensional culture mainly of tissue stem (TS) cell is regularly conducted for the purpose of a regeneration medical care. Use of embryonic stem (ES) cells will be initiated soon, although its ethical aspect is actually limited. Nevertheless, any of these technologies is far from the achievement of a regenerated organ capable of exerting functions sufficiently. On the other hand, a human organ and tissue bank is attempted to be established and maintained as an opponent to a genome-derived pharmaceutical developed by manufacturers of medicines. Under such circumstances, formation of regenerated tissue by stratifying human-derived normal tissues and inducing a differentiation in a more simple and reliable manner when compared with a prior art is expected greatly, and its realization is a significant objective, since a system for predicting the effects and the side effects of, or a system for assaying the sensitivity to a chemical substance mainly for a pharmaceutical can be constructed by obtaining a relevant organ model from the respective regenerated tissue.
Among current systems for assaying the effects of or the sensitivities to pharmaceuticals, a histoculture drug response assay (HDRA) using a collagen gel is known as a relatively effective means.
However, the HDRA has a problematically lower clinical true positive rate which is less than about 60%. Since the HDRA has a true negative rate of 80% or more, it is employed in a medical care practice only for screening for a non-effective anti-cancer agent in US. It is not regarded to be a recognized custom-made therapy which allows a most effective drug to be selected. Nevertheless, it is regarded as a highly advanced medical technology in Japan, although most of clinical practitioners are disappointed by the fact that it can select an effective drug at a probability as low as about 50%.
It fails also in assaying any side effect on normal tissues simultaneously.
A known method other than the HDRA is a CG-DST (collagen gel droplet embedded culture sensitivity test). However, this method involves cancer cells growth failure (no growth even in control) us high as 25% or more and gives an unsuccessful result at a rate as seriously high as 30% or more including the contamination rate, although its true positive rate is improved markedly to a level as high as 70 to 83%. Thus, when multiplying these two rates, the sensitivity can eventually be assayed only in 60% of the patients. Also from the data of the ovarian cancer, the assumption may vary depending on the tissue types. The potency of any side effect on normal tissues cannot be assayed also by this method.
Accordingly, any of the cancer therapy sensitivity tests of the prior art cannot predict the side effects on normal tissues simultaneously, even if it can evaluate the sensitivity of cancer cells or tissue to a therapy. It is far from an ideal custom-made therapy enabling the selection of a drug having fewer side effects.
Also in view for example of the current state described above, an assumption of the effects of and the sensitivity to a pharmaceutical should be enabled as soon as possible by obtaining a high level detection and evaluation system using regenerated tissues.
Accordingly, an objective of the invention is to overcome the limitations and the problems associated with the prior art described above, to obtain regenerated tissues simply and reliably by a 3-dimensional culture from a human-derived normal tissue as a base, and to provide, while utilizing the formers, a method for constructing a system for predicting the effects and the side effects of a chemical substance such as a pharmaceutical using thus regenerated tissues as a respective organ model or a system for predicting the sensitivity and the like.